The present invention relates to an improvement in the methods used to apply resin to raw materials such as wood chips used in the manufacture of construction material such as oriented strand board (OSB). More specifically, to a mechanism that applies the liquid resin that is less susceptible to the common problems of excessive wear and clogging that are associated with such resin application devices and also which are mounted within an application assembly in a manner that allows for their easy removal and replacement in the case of necessary maintenance.
In the construction industry today it is very common to use composite materials in the manufacture of such things as housing and other types of buildings where they are used most commonly as outer sheathing in place of more expensive materials like plywood. In the manufacture of these composite products, a large number of small particles of raw material is fed into a rotating drum where they are suspended within its interior. Additionally, the interior of the drum contains a plurality of resin atomizer units which disperse a fine fog of atomized resin into the interior of the drum. This resin fog entirely coats the exterior surface of the individual pieces of raw material so that they may be bound together in a specific form in a later manufacturing process upon being removed from the drum.
While this process produces quality OSB and other similar products, there are a number of problems specifically associated with the resin atomizer units that are commonly encountered during the manufacturing process. The first of these is that the resin, by its nature, has high adhesion properties which causes it to stick to the interior surfaces of the atomizer unit. One solution to this problem was offered in U.S. Pat. No. 5,914,153 issued to Swink et al. which provided a method of introducing a solvent into the atomized unit at specific time intervals during operation. While this system does reduce the adhesion problems, it does not entirely eliminate them partially due to the fact that the current atomizer units are constructed of aluminum or other metallic alloy to which the resin easily bonds. Additionally, the most commonly used resin in the industry is phenol-formaldehyde which has a very high alkaline content and is very corrosive and tends to corrode the critical components of the atomizer unit. These two factors create a situation in which the resin coating drums must periodically shutdown for cleaning and/or parts inspection or replacement. This is obviously an undesirable condition as it tends to increase downtime to the production line which lessens profits.
Another problem in the prior art is the manner used to attach the atomizer units in the proper location within the drum. The method commonly employed to attach the resin atomizer to the header pipe within the rotating drum is to use a plurality of bolts to secure it to a mounting plate extending from the header pipe. While this provides a secure method of resin atomizer attachment, it makes servicing the units troublesome and time consuming as a technician must at times extend himself into the drum to gain access to the mounting bolts. This makes the servicing procedure cumbersome at best and can add to the overall downtime of the production line, not to mention the unnecessary addition of difficulty and danger to the person actually performing the servicing operations.
From the forgoing discussion it can be seen that it would be desirable to provide a mechanism by which the raw materials for the manufacture of composite construction materials such as OSB can be effectively coated with adhesion resin in a manner that would reduce the production line down time associated with the necessary cleaning and maintenance required by today""s resin atomizers and extend the useable life of their critical components. Additionally, it can be seen that it would be advantageous to provide a means by which the resin atomizers could be easily removed and reinstalled to their point of attachment within the rotating drum to facilitate easy maintenance. These improvements in the design of resin atomizers would lead to greater efficiencies in the production of construction materials such as OSB which would in turn lead to better products and improved operator profits.
It is the primary objective of the present invention to provide a method of constructing resin atomizers that would decrease the tendency of the resin to adhere to the surfaces of the operational components of the atomizer and also limit the resin""s tendency to erode the critical resin passageways of the resin cone and housing.
It is an additional objective of the present invention to provide such a method of constructing resin atomizers in a manner that would facilitate their easy removal and reinstallation from their point of attachment within the rotating drum used to coat the raw materials prior to their final assembly into OSB sheathing.
It is a further objective of the present invention to provide such a method of constructing resin atomizers of a material that not only resists the adhesion and wear problems associated with the applications of such resins, but also is of a light weight which enhances a technician""s ability to handle and manipulate them during maintenance.
These objectives are accomplished by constructing a resin atomizer unit from a variety of ultra high molecular weight (UHMW) plastics. The use of these materials benefits in the construction of a resin atomizer both in its natural resistance to the adhesive qualities of the resin and in its relatively low weight when compared to the metallic alloys that were previously used in their construction.
The construction of OSB and other similar composite building materials is accomplished by introducing a large amount of small individual pieces of a raw material such as non-uniformly sized wood chips into a large rotating drum. The interior of the drum is lined with a plurality of inwardly extending fins which protrude uniformly a short distance from their point of attachment to the interior wall of the drum. The purpose of the fins is to agitate the pieces of raw material contained within the drum so that they are constantly tumbling through its center. With the wood chips so suspended and tumbling in this manner, the resin atomizer can evenly apply the adhesive resin to the exterior of the chips without the chips having to contact the surface of the application device. Once the application process has been completed, the wood chips are removed from the drum and processed into their final configuration.
The interior of the rotating drum also contains the header pipe which enters it from one end and which serves two purposes for the operation of the drum. The first of these is to provide a point of attachment for the plurality of resin atomizers contained within the drum. The second purpose of the header pipe is to provide a protected conduit through which the resin and other necessary chemicals or solvents can be piped to supply the resin atomizers during the operation of the resin coating operation in the production of OSB.
The plurality of resin atomizers are attached to the header pipe by the use of an equal plurality of attachment pipes which extend from the header pipe into the interior of the rotating drum. The inward edge of the attachment pipes are fitted with ring-shaped mounting flanges that contain an inner passageway and are machined in a manner so that their outer edges match the outside diameter of the atomizer units. Additionally, the mounting flanges are equipped with a plurality of bolt mounting holes which provide a mechanism by which the atomizer mount can be securely attached.
The mounting of the atomizer unit within the rotating drum is accomplished by separately bolting the atomizer mount flange to the pipe mount flange. The lower edge of the atomizer mount flange is equipped with a raised mount ring shoulder which matches in form and diameter to the body ring shoulder on the upper edge of the atomizer body. When these two components are fitted together, their connection is facilitated by the use of the ring clamp which encircles this connection and firmly holds the atomizer body to the atomizer mount flange. Additionally, the ring clamp is equipped with a release handle which provides a means by which it can be opened up and removed to quickly and easily remove and reinstall the atomizer body during maintenance or repair.
The resin atomizer unit is primarily comprised of an exterior atomizer body which is cylindrical in shape with a hollow interior. The interior houses an electric motor which is attached via a drive shaft to the resin cone at the most forward end of the atomizer body. The interior of the atomizer body is also equipped with a series of passages and components which are designed to channel the resin pumped into it to the resin well built into the back of the resin cone. The resin is supplied to the present invention by the resin feeder line coming from the interior of the header pipe and is passed through the resin plate located between the electric motor and resin cone. The purpose of the resin plate is to direct the flow of resin into the resin well in the back of the resin cone so that it can be properly distributed by the action of the resin cone.
The purpose of the electric motor is to spin the resin cone at a very high rate of speed. The spinning of the resin cone forces the resin contained within the resin well out of a plurality of small orifices that surround the outer edge of the central cone disc and into the cavity formed by the cone lip which extends around and forms the most forward edge of the resin cone. This method of resin delivery breaks it down into a very fine cloud of resin droplets which is the optimal consistency to properly coat the raw material contained within the rotating drum. Additionally, the most forward edge of the atomizer body has a beveled surface that is angled diagonally away and down from the center of the atomizer body. The angle created by this bevel is such that the air flow around it tends to carry the resin droplets away from the atomizer body which helps to limit the build up of hardened resin on the outer surface of the resin atomizer body. This is important to the operation of the present invention as the build up of resin on the operational surfaces tends to limit its efficiency.
The atomizer body and resin plate of the present invention are constructed of ULTRA HIGH MOLECULAR WEIGHT plastic, commonly and hereinafter referred to as UHMW, which has a number of properties that are beneficial for use in these types of applications. The first of these is that it is naturally resistant to the adhesive properties of the resins that are used in the manufacturing process of OSB. This property of UHMW plastic means that the components of the present invention that are constructed of UHMW will be less susceptible to the clogging and fowling problems associated with the use of metallic alloys or other similar materials. Another beneficial property of the UHMW plastic for use in this application is that it is also naturally resistant to the corrosive nature of the resins that are used. With other materials, the resin passing through the resin dispersion holes tends to bore the holes out in a relatively short period of time which affects the balance of the resin cone which can impart a wobbling motion to it and destroy the associated bearings in a short period of time. The use of the corrosive resistant UHMW plastic extends the life of these components which reduces downtime of the production line that was due to the constant need for replacing these parts. Finally, the components made from the UHMW plastic are much lighter than those constructed from metallic alloys which makes the present invention easier to work with during required maintenance procedures.
The resin cone component of the present invention is machined from Acetal which is also known as polyacetal, polyoxymethylene, or polyformaldehyde, which is a high performance engineering polymer. The use of this material to produce the resin cone provides a component that is more resistant to both the corrosive and adhesive properties of the resin than the previously used metallic alloys. Additionally, the resin cone component of the present invention is also significantly lighter than those of the prior art and therefore places less stress on its electric motor which in turn leads to a longer life span for the motor and bearings. Finally, the use of these materials allows the components of the present invention to be manufactured with thinner walls which creates larger clearances and passages for the resin to flow in critical areas which helps reduce the incidents of resin build up and clogging, therefore reducing production downtime.
Therefore, the present invention provides a method of constructing the spinning disc resin atomizers used in the manufacture of OSB which greatly reduces the resin""s tendency to adhere to the critical surfaces of the atomizer during operations. This reduction of resin adhesion improves the performance of such system as it increases the atomizer""s efficiency and reduces downtime associated with require cleaning. Additionally, the present invention can also be equipped with a solvent application device that can further reduce the resin""s tendency to adhere which further extends the invention""s productivity. The materials used in the construction of the present invention also have the beneficial quality of resisting the abrasive nature of the resin which lessens the need for periodic component replacement and leads to further increases in productivity in much the same manner as described above. Another benefit of the use of the materials herein described is the construction of the present invention also lessens its overall weight which makes any maintenance that may be required much easier. Finally, the quick release method of attaching the individual resin atomizers to the header pipe within the rotating drum also enhances the ease by which the invention can be serviced and thereby leads to greater efficiencies in the production of OSB.
For a better understanding of the present invention reference should be made to the drawings and the description in which there are illustrated and described preferred embodiments of the present invention.